drm/amdgpu: add scheduler dependency callback v2

This way the scheduler doesn't wait in it's work thread any more.

v2: fix race conditions

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>

2 files changed, 25 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
index 205cb887d023..2f5d1f0da8e5 100644
--- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
+++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
@@ -192,14 +192,36 @@ void amd_sched_entity_fini(struct amd_gpu_scheduler *sched,
 	kfifo_free(&entity->job_queue);
 }
 
+static void amd_sched_entity_wakeup(struct fence *f, struct fence_cb *cb)
+{
+	struct amd_sched_entity *entity =
+		container_of(cb, struct amd_sched_entity, cb);
+	entity->dependency = NULL;
+	fence_put(f);
+	amd_sched_wakeup(entity->scheduler);
+}
+
 static struct amd_sched_job *
 amd_sched_entity_pop_job(struct amd_sched_entity *entity)
 {
+	struct amd_gpu_scheduler *sched = entity->scheduler;
 	struct amd_sched_job *job;
 
+	if (ACCESS_ONCE(entity->dependency))
+		return NULL;
+
 	if (!kfifo_out_peek(&entity->job_queue, &job, sizeof(job)))
 		return NULL;
 
+	while ((entity->dependency = sched->ops->dependency(job))) {
+
+		if (fence_add_callback(entity->dependency, &entity->cb,
+				       amd_sched_entity_wakeup))
+			fence_put(entity->dependency);
+		else
+			return NULL;
+	}
+
 	return job;
 }
 
diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
index e797796dcad7..2af0e4d4d817 100644
--- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
+++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
@@ -45,6 +45,8 @@ struct amd_sched_entity {
 	spinlock_t			queue_lock;
 	struct amd_gpu_scheduler	*scheduler;
 	uint64_t                        fence_context;
+	struct fence			*dependency;
+	struct fence_cb			cb;
 };
 
 /**
@@ -89,6 +91,7 @@ static inline struct amd_sched_fence *to_amd_sched_fence(struct fence *f)
  * these functions should be implemented in driver side
 */
 struct amd_sched_backend_ops {
+	struct fence *(*dependency)(struct amd_sched_job *job);
 	struct fence *(*run_job)(struct amd_sched_job *job);
 	void (*process_job)(struct amd_sched_job *job);
 };